Filter group

ABSTRACT

A filter cartridge including a filter membrane and at least a support element fixed to the filter membrane, the support element being provided with at least a snap-engaging element suitable for snap-engaging to a support body following a reciprocal translation between the filter cartridge and the support body along a nearing axis, the support element further including a disengaging device suitable for disengaging the snap-engaging element from the support body following a reciprocal rotation between the filter cartridge and the support body about the axis.

TECHNICAL FIELD

The present invention relates to a filter cartridge and a relativefilter group. The invention mainly relates to a filter group forcomburent air which is conveyed internally of internal combustionengines; however the filter might be used for filtration of otherfluids, such as for example exhaust gases, oils or fuel.

In greater detail, the invention relates to air filter groups,especially in applications in which a high flow of air to be filtered isrequired, such as for example—in motoring applications—lorries, buses,commercial vehicles and work machines, or in industrial applications.

BACKGROUND ART

As is known, the filtering of air in the motoring or industrial field isgenerally obtained by means of a filter group which comprises anexternal casing provided with an inlet for fluid to be filtered and anoutlet of filtered fluid, and a filtering cartridge suitable fordefining a chamber, for example external, communicating with the inletof the fluid to be filtered.

In this way, the fluid that flows from the, inlet towards the outlet ofthe filter is forced to cross the filter membrane which retains theimpurities possibly present therein.

A typical filter cartridge comprises a tubular filter membrane and twosupport plates, upper and lower, which are fixed to the opposite ends ofthe filter membrane.

At least one of the support plates is commonly provided with a centralopening, aligned with the longitudinal axis of the filter membrane,through which the internal volume of the filter membrane is placed incommunication with the inlet of the fluid to be filtered, in a case inwhich the filter membrane is configured such as to be crossed frominside towards outside, or with the outlet of the fluid, to be filtered,in a case in which the filter membrane is configured such as to becrossed from outside towards inside.

The casing, in these types of air filters, generally comprises a supportbody, conformed as a flange (or plate), provided with a hole definingthe outlet and set in communication with the internal chamber of thefilter membrane.

As is known, due to the high flow rate of air to be subjected tofiltering for this type of filter group, the filter cartridge mustnecessarily exhibit considerable dimensions, at least such as to enablepassage of the air without exceeding certain values as set by the normsand standards in the sector, which for example impose low load lossvalues.

Because of the significant dimensions of the filter cartridge, theinstallation and replacement thereof in these applications can representa problem connected to the step of moving and manoeuvring it.

In an attempt to alleviate the work of the personnel specialised ininstalling the filter cartridge, the prior art provides varioussolutions for removably engaging the filter cartridge to the casing (forexample to a cover of a beaker body or a support plate).

A first type of these solutions comprises the use of a bayonet-typeengagement: these types of engagements comprise at least two profiledprotrusions defined in the filter cartridge, each of which is destinedto be inserted in a special groove realised in the support flange, suchthat the engagement is enacted by a short axial translation of thefilter cartridge towards the support flange and a consequently smallrotation about the axis of the filter cartridge.

These bayonet couplings, however, exhibit some drawbacks due mainly tothe required complexity of the engagement.

It is usually necessary to provide means for blocking the reciprocalrotation between the filter cartridge and the support flange (orcasing), which are for example flexible devices, grooves withlabyrinthine profiles or threaded organs.

These blocking systems are on the one hand not particularly reliable andnot very resistant over time, especially after repeated replacements ofthe filter cartridge, and on the other hand they lead to an increase inproduction costs of the filter cartridge and the casing (support flange)as well as costs over time for maintenance operations for replacing thefilter cartridge.

A second known type of engagement, alternative to the above-describedbayonet couplings, comprises axial snap-engagements, which are howevernot used in air filter groups, where there are high flow rates of air tobe filtered, as the weight and large dimensions of the filter cartridgeswould made the exact positioning of the engaging means difficult toassess.

Further, the need to ensure engaging of a filter cartridge ofconsiderable weight would necessarily lead to realising an axialsnap-fit that would be hard to remove.

DISCLOSURE OF INVENTION

An aim of the present invention is to obviate the above-mentioneddrawbacks of the prior art, with a solution that is simple, rational andrelatively inexpensive.

These aims are attained by the characteristics of the invention reportedin the independent claim. The dependent claims delineate preferredand/or particularly advantageous aspects of the invention.

In particular, the invention provides a filter cartridge comprising afilter membrane and at least a support element fixed to the filtermembrane of at least a snap-engaging element destined to snap-fit to asupport body following a reciprocal translation between the filtercartridge and the support body along a nearing axis.

In the invention, the support element comprises disengaging meansdestined to disengage the snap-fitting element from the support bodyfollowing a reciprocal rotation between the filter cartridge and thesupport body with respect to the axis.

Thanks to this solution, the disengaging operations of the filtercartridge are facilitated, and it is possible to use hooking elementswhich are sufficiently rigid and resistant and suited to supportingfilter cartridges of considerable weight.

Further, thanks to this solution the filter group is reliable in use, isrelatively inexpensive and simple to realise with respect tobayonet-coupling systems commonly used in the sector.

The filter membrane advantageously exhibits an elongate shape with aprevalent development along the axis which is a longitudinal axis of thefilter cartridge; further, for example, the filter membrane exhibits atransversal section that is substantially constant along thelongitudinal axis.

In the example, the engaging means comprise an elastically yieldingtooth destined to give rise to a complementary fit with the support bodyby means of a snap-coupling in a transversal direction with respect tothe axis of the filter cartridge, for example following a limited axialmovement of the filter cartridge with respect to the support plate, suchas to removably constrain the support body and the filter cartridge toone another.

Thanks to this solution, the installation of the filter cartridge isdecidedly simple and rapid.

A further aspect of the invention is that the tooth comprises a flankwhich is inclined with respect to a radial plane, the inclined flankdefining the disengaging means destined to cooperate with the supportbody for disengaging the tooth from the support body, for examplefollowing a limited rotation with respect to the axis of the filtercartridge.

This means that the operations of removing the filter cartridge from thesupport body for its replacement are particularly advantageous andrapid. The invention further provides a filter group which comprises asupport body provided with at least a passage hole for a fluid and atleast a respective engaging element which snap-fits to the filtercartridge, which is associated to the support body, such as to delimit aclosed volume communicating with the passage hole.

The respective engaging element of the support body advantageouslycomprises an engaging seating provided with an abutting surface and theengaging element of the filter cartridge is destined to removably engageto the abutting surface.

In particular, the support body of the filter group comprises at least aguide surface, associated to the engaging surface, destined to guide theengaging element of the filter cartridge towards the abutting surface.

Thanks to this solution, the filter cartridge is always guided towardsthe engaging seating and therefore the alignment of the engagingelements with the seating itself is facilitated; in this way theengagement can be achieved by means of a contained translation of thefilter cartridge towards the body destined to support it.

An aspect of the invention is, further, that the support body of thefilter group comprises two of the guide surfaces that converge towardsthe engaging seating, which guide surfaces respectively define aninclined plane, with respect to the abutting surface, for the entry ofthe engaging element into the engaging seating.

In this way, the filter cartridge is guided towards the respectiveengaging seating, simply by sliding the engaging elements on one of theguide seatings, independently of its position with respect to thesupport plate.

The engaging means advantageously comprise a disengaging ramp which isassociated to the engaging seating realised in the support body, fordisengaging the engaging element of the filter cartridge from theabutting surface of the engaging seating.

In this way, the disengaging operations of the filter cartridge from thebody destined to support the filter cartridge are even easier, morerapid and more reliable.

The disengaging ramp defines a plane inclined in a transversal directionwith respect to the axis of the filter cartridge, which is destined toflex the tooth in that direction, distancingly from the engagingseating, following a limited rotation of the filter cartridge withrespect to the axis thereof.

Still more advantageously, the inclined flank of the tooth of the filtercartridge and the disengaging ramp of the engaging seating are such asto go into dragging contact following an axial rotation of the filtercartridge with respect to the support body, for disengaging the toothfrom the abutting surface.

Further, the support body comprises a flange, destined to be solidly andsealedly associated to the filter cartridge, and an appendage derivingfrom the flange; the engaging seating being realised at the appendage.

Further, with the aim of ensuring hermetic sealing between the supportplate and the filter cartridge, the filter group comprises at least aseal ring, for example associated to the filter cartridge, interposedbetween the filter cartridge and the support body and destined to becompressed between them following the snap-engagement between theengaging element of the filter cartridge and the engaging seatingrealised in the support body.

BRIEF DESCRIPTION OF DRAWINGS

Further characteristics and advantages of the invention will emerge froma reading of the following description, provided by way of non-limitingexample, with the aid of the figures of the accompanying drawings.

FIG. 1 is an axonometric view in longitudinal section of a filter groupof the present invention.

FIG. 2 is detail II of FIG. 1.

FIG. 3 is a lateral view of a filter cartridge of the filter group ofFIG. 1.

FIG. 4 is a view from above of FIG. 3.

FIG. 5 is an axonometric section view of the upper support plate of thefilter cartridge of FIG. 3.

FIG. 6 is a lateral view of FIG. 5.

FIG. 7 is enlarged detail VII of FIG. 4.

FIG. 8 is a detail of a lateral view of the filter group of FIG. 1.

FIG. 9 is a view from above of FIG. 8.

FIG. 10 is section X-X of FIG. 8.

FIG. 11 is an enlarged detail of FIG. 10.

BEST MODE FOR CARRYING OUT THE INVENTION

The filter group 10 illustrated in FIG. 1 is an air filter destined tobe applied in the motor vehicle sector, in particular for motors ofheavy duty vehicles such as lorries, buses, commercial vehicles orself-propelling work vehicles. The filter group 10 comprises an externalcasing, comprising a beaker-shaped body 11 (visible in FIG. 3) and aplate-shaped support body, denoted in its entirety by 20 in the figures,which is suitable for sealedly closing the beaker body 11 (for exampleby means of threaded organs or the like, directly or indirectly by meansof a cover) and for supporting a filter cartridge 30 suitable for beingarranged internally of the beaker body.

The beaker body 11 further defines an inlet hole 12 for the air to befiltered.

The support plate 20 is defined by an annular flange 21 provided with anoutlet conduit 22, defining the outlet passage hole of the filtered air,which for example is located superiorly to the annular flange.

On the opposite side with respect to the outlet conduit 22, the supportplate 20 comprises a hollow appendage 23 projecting inferiorly of theannular flange 21 and such as to perimetrally delimit the annularflange.

A plurality of engaging seatings 24 are afforded in the appendage 23,for example lateral slots, which are such as to define respectiveabutting surfaces 25 that are substantially flat and parallel to theannular flange 21.

Each abutting surface 25 is defined by the lower edge of the lateralslot realised in the appendage 23.

The appendage 23, and in particular the lower edge 26 thereof, exhibitstwo guide surfaces 27 at each engaging seating 24, which guide surfaces27 are arranged on opposite sides with respect to the respectiveengaging seating 24 and are inclined such as to converge towards theengaging seating (each pair of guide surfaces is therefore associated tothe respective engaging seating, as it is realised on the appendage 23).

Each guide surface 27 exhibits an inclined plane with respect to theplane defined by the abutting surface 25 such as to realise an entryzone towards the respective engaging seating.

In other words, the lower edge 26 of the appendage 23 exhibits asubstantially undulated conformation, defined by the guide surfaces 27,which exhibit an inclination of an acute angle with respect to theperpendicular direction to the longitudinal axis A, the inclinations ofeach pair of guide surfaces 27 being opposite in direction, such as toconverge towards the centre thereof.

Between the two guide surfaces 27, the lower edge 26 exhibits asubstantially flat profile which is parallel to the abutting surface 25;substantially a bearing limb of the appendage 23 distances the flatprofile of the lower edge 26 and the abutting surface 25.

The appendage 23, in proximity of each engaging seating 24, exhibits adisengaging ramp 28 (visible in the detail of FIG. 11), which is definedin the internal lateral wall of the appendage 23; the disengaging ramp28 is realized by an inclined connecting surface between the externalsurface and the internal surface of the appendage 23, which defines asalient profile with a relatively low slope between the external surfaceand the internal surface of the appendage.

The plan profile of the appendage 23 exhibits, at the disengaging ramp28, a progressively growing thickness (in a radial direction) startingfrom the lateral slot defining the engaging seating 24.

In the example illustrated in the figures, the appendage 23 exhibits sixengaging seatings 24 that are equidistant and aligned in plan view on animaginary circumference that is coaxial to the annular flange 21.

The annular flange 21 is substantially sealedly associated to the filtercartridge 30: the lower surface of the annular flange 21, destined toface the filter cartridge 30, defines a rest zone for a seal ring 40,which is destined in use to be compressed between the annular flange 21and the filter cartridge 30, such as to guarantee hermetic closurebetween the inlet conduit 22 and the filter cartridge.

The filter cartridge 30 comprises an upper support element, in theexample an upper support plate 31, and a lower support plate 32, whichare fixed to opposite ends of a tubular filter membrane 33, whichdefines and delimits a substantially-cylindrical internal volume of thefilter cartridge 30.

The upper support plate 31 exhibits a central hole 34 which is centredon the longitudinal axis A of the filter membrane 33, which is incommunication, by means of the central hole of the annular flange 21,with the outlet conduit 22 of the filtered air.

Thanks to the above-described configuration, the filter cartridge 30defines a chamber 35, coinciding with the internal volume of the filtermembrane 33, which communicates with the outlet conduit 22 of the air tobe filtered.

A plurality of engaging teeth 36 (also referred to as engaging elementsherein) are fashioned on the surface of the upper support plate 31,opposite the filter membrane 33, which engaging teeth 36 rise from theupper support plate and define an engaging surface 37 facing towards theupper support plate 31. The engaging surface 37 is substantially planarand lies on a plane that is substantially perpendicular to thelongitudinal axis A of the filter membrane 33.

Each engaging tooth 36 further comprises an inclined flank 38 (i.e.which exhibits at least an inclined lateral portion with respect to theradial direction), substantially having a complementary shape to thedisengaging ramp 28 realised in the appendage 23.

The inclined portion of the inclined flank 38 defines a bevelling on alateral flank of the engaging tooth 36, such as to facilitate thesliding of the engaging tooth 36 on the disengaging ramp 28, or in anycase on the lateral wall of the engaging seating 24, of the appendage23, following a short rotation (in a disengaging direction indicated bythe broken-line arrows in FIG. 10) with respect to the longitudinal axisA of the filter cartridge 30, in relation to the support plate 20.

The flank opposite the inclined flank 38 of the engaging tooth 36 issubstantially straight (taking “straight” to mean that it exhibits aflat profile lying on a radial plane), and the engaging seating 24exhibits a respective straight flank, such as to stably arrest thereciprocal rotation between the filter cartridge 30 and the supportplate 20 with respect to the longitudinal axis A in the oppositedirection to the disengaging direction.

In particular, in the example reported in the figures there are sixengaging teeth 36 which are aligned in plan view with respect to animaginary circumference that is concentric to the hole defined in theupper support plate 51, and are reciprocally equidistant.

An annular relief 39 afforded in the upper support plate 31 and emergingtherefrom is provided in a zone internal of the engaging teeth 36, whichannular relief 39 supports the seal ring 40 which in use is compressedbetween the annular projection 39 and the annular flange 21.

With reference to the above description, the filter group 10 functionsas follows.

To assemble the filter group 10, it is sufficient to engage the engagingteeth 36 of the filter cartridge 30 in the respective engaging seatings24 of the support plate 20, by nearing the filter cartridge 30 in anaxial direction; in any angular position the filter cartridge 30 happensto be in, the engaging teeth 36 initially contact the lower edge 26 ofthe appendage 23.

Should the engaging teeth 36 not be already aligned with the engagingseating 24, the teeth 36 contact a portion of the lower edge 26 havingone of the guide surfaces 27; when the filter cartridge 30 is pressedaxially towards the support plate 20 (and/or rotating slightly withrespect to the longitudinal axis A) the engaging teeth 36 slide on theguide surfaces 27 until they align with the respective engaging seatings24.

In this position, with a simple further axial translation of the filtercartridge 30, such as to enable the engaging tooth 36—with a radialflexing—to pass over the bearing lip of the appendage 23 which separatesthe lower edge 26 thereof from the engaging seating 24, the engagingteeth 36 snap-engage with the respective lateral slots realised in theappendage 23 and thus also the engaging seatings 24.

In particular, the engaging surface 27 of each engaging seating 26stably rests on each abutting surface 25 of the respective engagingseating 24.

To remove the filter cartridge 30 from the engagement with the supportplate 20 it is sufficient to slightly rotate the filter cartridge in thedirection (denoted in FIG. 10) in which the inclined flank 38 of theengaging tooth 36 is brought into contact with the disengaging ramp 28of the engaging seating 24.

By continuing the rotation of the filter cartridge 30 in the samedirection, the reciprocal dragging between the inclined flanks 38 andthe disengaging ramps 28 flexes the engaging teeth 36 radially, suchthat each engaging surface 37 distances from the respective engagingsurface 25; in this way the engaging teeth are free to slide in an axialdirection distancingly from the support plate 20, freeing the filtercartridge 30 which can therefore be replaced.

In the embodiment shown in the figures and described herein above, theengaging elements 36 are associated the filter cartridge 30 (inparticular to the upper support plate 31 thereof) and the engagingseating 24 is realised in the support late 20, though alternatively theengaging seating could be afforded in the filter cartridge (for examplein the upper support plate thereof) and the engaging element, i.e. theengaging teeth, in the support plate or in the cover of the casing orother body destined to support the filter cartridge.

Further, a technical expert in the sector might make other numerousmodifications of a technical-applicational nature to the filter group 10as described above, without its forsaking the ambit of the invention asclaimed herein below.

1. A filter cartridge comprising: a tubular filter membrane; at least asupport plate being fixed to the filter membrane, the filter cartridgehaving a longitudinal axis, the support plate being provided with atleast an elastically yielding tooth that can yield in a radial directionfollowing an axial compression thereon in a direction parallel to thelongitudinal axis, and defines an engaging surface facing towards thesupport plate, in which the elastically yielding tooth comprises a flankwhich is inclined with respect to a radial plane of the filter cartridgeand can flex the elastically yielding tooth in a redial directionfollowing a dragging rotation of the filter cartridge around thelongitudinal axis.
 2. The filter cartridge of claim 1, wherein thefilter membrane exhibits an elongate shape with a prevalent developmentalong the longitudinal axis (A). 3-13. (canceled)